The Stewart’s Creek Habitat Restoration Project is entering its final planning stages.

The project, which seeks to replace the current three-foot diameter culvert running under Ocean Street with a four-foot by six-foot one that will aid in restoring tidal flow to the lower portion of the creek, has been in the works since 2003.

Another aspect of the project will involve dredging in the shallow open water area of the creek, with the dredge sediment used to rebuild salt marsh adjacent to the open water.

“It’s a great restoration,” said Rob Gatewood, Town of Barnstable Conservation Administrator. “We hope to restore it to the way it appeared around 1960, before the fresh water elevation drowned the salt marsh.”

The project is funded half by the Army Corps of Engineers and half by the town.

“It hasn’t been bid, but we estimate the cost to be around $1.2 million,” Gatewood explained.

If everything goes smoothly, construction would begin in September of 2011 and conclude before the end of the year, with almost immediate benefit.

“It will become an estuary right away,” Gatewood noted. “An estuary that receives tidal flow twice a day. The salt marsh restoration will take, my guess, about five years.”

He also added that there may be a diminishment in the health of the tall reed stands, an invasive species known as phragmites that can grow as tall as 12 feet. While the higher salinity would degrade these, it would also give a chance for native marsh grasses to reestablish themselves.

“We’re happy to be proceeding with the remainder of our permits,” Gatewood said. “We believe our way looks reasonably clear for construction.”